Basics of networking
The physical layer in Networking
These physical media can be used to exchange information once this information has been converted into a suitable
electrical signal. Entire telecommunication courses and textbooks are devoted to the problem of converting analog
or digital information into an electrical signal so that it can be transmitted over a given physical link. In this book,
we only consider two very simple schemes that allow to transmit information over an electrical cable. This enables
us to highlight the key problems when transmitting information over a physical link. We are only interested in
techniques that allow to transmit digital information through the wire and will focus on the transmission of bits,
i.e. either 0 or 1.
In computer networks, the bit rate of the physical layer is always expressed in bits per second. One Mbps is one
million bits per second and one Gbps is one billion bits per second. This is in contrast with memory specifications
that are usually expressed in bytes (8 bits), KiloBytes ( 1024 bytes) or MegaBytes (1048576 bytes). Thus
transferring one MByte through a 1 Mbps link lasts 8.39 seconds.
Types of Networking
Computer networking has become an integral part of business today. Individuals, professionals and academics have also learned to rely on computer networks for capabilities such as electronic mail and access to remote databases for research and communication purposes. Networking has thus become an increasingly pervasive, worldwide reality because it is fast, efficient, reliable and effective. Just how all this information is transmitted, stored, categorized and accessed remains a mystery to the average computer user.
This artical explain the basics of some of the most popular technologies used in networking, and will include the following:
Types of Networks – including LANs, WANs and WLANs
The Internet and Beyond – The Internet and its contributions to intranets and extranets
Types of LAN Technology – including Ethernet, Fast Ethernet, Gigabit Ethernet, 10 Gigabit Ethernet,
ATM, PoE and Token Ring
Networking and Ethernet Basics – including standard code, media, topographies, collisions and CSMA/CD
Ethernet Products – including transceivers, network interface cards, hubs and repeaters